Lightweight air vehicle and pneumatic launcher

ABSTRACT

A portable unmanned air vehicle and launcher system is provided that includes a foldable unmanned air vehicle having a pressure tube; a launch gas reservoir for holding launch gas; a launch tube operatively connected to the launch gas reservoir and having a free end that is positioned in the pressure tube of the air vehicle; a free piston positioned within the launch tube; and a free piston stop to prevent the free piston from leaving the launch tube. A first portion of the launch gas in the launch gas reservoir is released into the launch tube and forces the free piston from an initial position to an end position at which the free piston is stopped by the free piston stop.

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/448,472, filed Feb. 21, 2003.

BACKGROUND OF THE INVENTION

The present invention relates generally to lightweight air vehicles andlaunchers used for lightweight air vehicles, and more particularly tounmanned aerial vehicles and pneumatic launchers therefore.

Lightweight unmanned air vehicles are becoming very popular for varioususes including surveillance and package delivery in military and lawenforcement situations. Methods for making these UAVs smaller andlighter are needed to improve system transportability. Methods formaking them easier to use are needed to improve reliability. Methods forlaunching UAVs with minimal signature by making them quick and quiet tolaunch from a very limited space are needed to enable covert operation.There is a need, particularly in military applications, for atransportable, reliable and low signature UAV and launching system thatcan be carried by one person.

BRIEF SUMMARY OF THE INVENTION

The invention provides a lightweight UAV and a system for launching theUAV that is compact and lightweight so that, for example, a soldier caneasily carry the system as a backpack.

The invention incorporates design features and approaches that are moretransportable and reliable and are less detectable than conventionalmethods. Transportability is achieved by the small size and low weightof the design as well as a protective tube packaging approach. Alightweight materials and structural approach has been used to achievethe small size and low weight. A heavy and complicated launcher is notneeded. The outer tube of the launcher is also used as a protectivetransport tube. This tube, which totally encloses the air vehicle,prevents damage to the light aircraft structures when transported alongwith other military equipment and supplies to and from the theater ofoperations.

Reliability has been achieved by the invention by reducing the relianceon skilled and trained operators. Conventional small UAVs aretransported in pieces and assembled when needed. The invention istransported fully assembled and does not suffer reliability problemsassociated with lost, broken or improperly assembled individualcomponents. Conventional small UAV launcher methods involve proceduresand technologies that personnel must perform correctly to achieve asuccessful launch. Often the launch is unsuccessful which can damage theair vehicle. The invention involves a launch method that can beperformed correctly with significantly less training.

Signature reduction is achieved by a packaging approach, tube launchdesign and pneumatic launch design features. The packaging approacheliminates the need for air vehicle assembly at the launch location. Asa result, the activity of unpacking and assembling the air vehicle isnot needed and, therefore, can not be detected. The tube launch designrequires very little space to operate. Conventional small UAV launchtechniques can require a small field for launching while the inventioncan launch the UAV from minimal space such as, for example, within theconfines of a small bush. The noise reduction design features eliminatethe loud popping sound associated with conventional pneumatic launchmethods.

In some embodiments, a hold back mechanism is used to retain the airvehicle on a launch tube when a launch gas reservoir and the launch tubeare charged with pressurized gas. When the hold back mechanism isreleased, the air vehicle is propelled off of the launch tube by thepressurized gas. A free piston in the launch tube allows the air vehicleto be ejected while blocking the exhaust of remaining gas from thepressurized reservoir, thus greatly reducing the noise created duringlaunch.

Embodiments of the invention provide a launcher for launching a foldableunmanned air vehicle having a pressure tube, the pressure tube beingopen at a rear end and closed at a front end. The launcher including alaunch gas reservoir for holding launch gas; a launch tube operativelyconnected to the launch gas reservoir and having a free end forinserting into the open end of the pressure tube of the air vehicle; afree piston positioned within the launch tube; and a free piston stop toprevent the free piston from leaving the launch tube. A first portion ofthe launch gas in the launch gas reservoir is released into the launchtube and forces the free piston from an initial position to an endposition at which the free piston is stopped by the free piston stop.The movement of the free piston from the initial position toward the endposition in the launch tube occurs as the air vehicle launches.

Other embodiments of the invention provide a portable unmanned airvehicle and launcher system. The system including a foldable unmannedair vehicle having a pressure tube, the pressure tube being open at arear end and closed at a front end; a launch gas reservoir for holdinglaunch gas; a launch tube operatively connected to the launch gasreservoir and having a free end that is positioned in the pressure tubeof the air vehicle; a free piston positioned within the launch tube; anda free piston stop to prevent the free piston from leaving the launchtube. A first portion of the launch gas in the launch gas reservoir isreleased into the launch tube and forces the free piston from an initialposition to an end position at which the free piston is stopped by thefree piston stop. The movement of the free piston from the initialposition toward the end position in the launch tube occurs as the airvehicle launches.

Other embodiments of the invention provide a foldable unmanned airvehicle including a fuselage having a pressure tube portion forreceiving a launch tube of a pneumatic launcher; two wings, each wingbeing pivotably connected to the fuselage such that it pivots about apivot point; a wing retention mechanism that holds the wings in a foldedposition; a foldable tail connected to the fuselage; a tail retentionmechanism that holds the tail in a folded position; and a linkage thatlinks the wing retention mechanism to the tail retention mechanism suchthat release of one of the tail retention mechanism and the wingretention mechanism releases the other of the tail retention mechanismand the wing retention mechanism.

Further objectives and advantages, as well as the structure and functionof preferred embodiments will become apparent from a consideration ofthe description, drawings, and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following, more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings wherein like reference numbers generally indicate identical,functionally similar, and/or structurally similar elements.

FIG. 1 is a schematic sectional view of an air vehicle and launcher inaccordance with an embodiment of the invention;

FIGS. 2-6 are schematic views of various stages of launching inaccordance with an embodiment of the invention;

FIG. 7 is a partial sectional view of a detail in accordance with theinvention;

FIG. 8 is a schematic side view of an air vehicle being launched inaccordance with the invention;

FIG. 9 is a perspective view of an example of an air vehicle inaccordance with the invention;

FIG. 10 is a side view of a wing deployment mechanism in accordance withthe invention;

FIG. 11 is a perspective view of the mechanism shown in FIG. 10; and

FIG. 12 is a partial view of an example of a tail deployment mechanismin accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are discussed in detail below. Indescribing embodiments, specific terminology is employed for the sake ofclarity. However, the invention is not intended to be limited to thespecific terminology so selected. While specific exemplary embodimentsare discussed, it should be understood that this is done forillustration purposes only. A person skilled in the relevant art willrecognize that other components and configurations can be used withoutparting from the spirit and scope of the invention.

The invention provides a lightweight, unmanned air vehicle and alauncher for the air vehicle that can be carried by a single person in,for example, a battlefield situation. The air vehicle and launcher forma compact, lightweight unit that is durable and easily deployed by asingle person. The system launches the air vehicle with minimal noise,making the system particularly appropriate for stealth, covertoperations. The extremely low noise levels generated by launching areachieved by containing most of the gas used to launch the vehicle withinthe system and, thereby, substantially eliminating the gas release noisecommon with pneumatic launch mechanisms.

FIG. 1 shows an example of a system 10 in accordance with the invention.System 10 includes an air vehicle 100 and a launcher 200. Air vehicle100 has a pressure tube 110 that, in this example, forms a portion of afuselage 120 of air vehicle 100. Air vehicle 100 has, in this example,two wings 130 that are folded while air vehicle 100 is in launcher 200.A tail 140 is also shown schematically at the rear end of air vehicle100. A folded propeller 150 is also provided in this example. Inpreferred embodiments, an quiet, electric motor is used to power thepropeller.

Pressure tube 110 has an open end 112 and a closed end 114. Pressuretube 110 receives a launch tube (discussed below) of launcher 200 and isthe interface of energy transfer between launcher 200 and air vehicle100.

Launcher 200 has a tube 210 that provides an enclosure for the launchercomponents and air vehicle 100. Launcher 200 has a launch gas reservoir220 that stores a gas used to launch air vehicle 100. Appropriate gasesinclude, but are not limited to, air, nitrogen and helium. Attached tolaunch gas reservoir 220 is a launch tube 230 that extends into pressuretube 110 of air vehicle 100. A free piston 240 is located inside launchtube 230 and is permitted to slide freely between an end stop 250 and astop pin 260. A valve 280 may be provided to allow an operator controlover when gas is permitted to pass from launch gas reservoir 220 tolaunch tube 230.

A hold back mechanism 290 can be used to hold the air vehicle ontolaunch tube 230 when gas pressure is applied to launch tube 230. Atrigger release mechanism 291 can be provided to release hold backmechanism 290.

An example of a launch sequence is shown in FIGS. 2-6. FIG. 2 is asimplified view of the system immediately prior to launch (similar toFIG. 1). With hold back mechanism 290 engaged, pressurized gas fillinglaunch gas reservoir 220 will be applied to launch tube 230 and freepiston 240. FIG. 3 is a view of the system shortly after hold backmechanism 290 is activated and launch gas is allowed to transfer fromlaunch gas reservoir 220 to launch tube 230. In this view, air vehicle100 (schematically represented by pressure tube 110) has moved relativeto launch tube 230 under the force exerted on closed end 114 of pressuretube 110 by the launch gas that has moved from launch tube 230 intopressure tube 110. The arrows in FIG. 3 represent launch gas movingaround free piston 240 through spaces between free piston 240 and theinside wall of launch tube 230. The size and number of these spaces isimportant to properly regulate the amount of launch gas that passes byfree piston 240 during the launch procedure. If the spaces allow toomuch launch gas to pass by free piston 240, the result will be excessivegas loss which will result in an undesirable noise signature. In theextreme case, the entire volume of launch gas could be lost, creatingthe maximum noise signature. If the spaces are too restrictive and allowtoo little launch gas to pass by free piston 240, free piston 240 couldblock the open end of launch tube 230 before air vehicle pressure tube110 clears launch tube 230. When this happens, the launch energy isisolated from air vehicle 100 and launch performance (velocity) isreduced.

FIG. 4 shows free piston 240 at rest against end stop 250 of launch tube230 and pressure tube 110 preceding further away from launch tube 230.When free piston 240 is in this position, it is pressed against, andforms a seal with, end stop 250 to prevent any further launch gas fromescaping from the system. FIG. 5 shows pressure tube 100 clearing theend of launch tube 230. At this point, air vehicle 100 will be clear of,or almost clear of, tube 210 of launcher 200. After the launch iscomplete, free piston 240 has sealed most of the pressurized gas fromescaping the system.

To reuse the launcher, the operator has several options depending on thedesign features included in the launcher. In the simplest launcherdesign, the pressurized gas is vented to the atmosphere using a ventingneedle valve located, for example, between launch gas reservoir 220 andlaunch tube 230. Once the gas is vented, free piston 240 releases fromend stop 250 and an air vehicle can be installed and latched in positionusing hold back mechanism 290. To execute another launch, the launchermay need to be charged by an external pressure source. If the launcheris equipped with a valve 280, this can be closed off. Pressure insidelaunch tube 230 is vented to allow free piston 240 to fall to thepre-launch position. This venting can be accomplished by severalmethods, including: (1) a vent valve located between valve 280 andlaunch tube 230; (2) a slow leak like a pin hole in free piston 240which would slowly vent the chamber; or (3) a vent valve located in freepiston 240 that could be manually activated to vent the chamber. Oncelaunch tube 230 is vented, another air vehicle can be mounted. A smallboost charge from an external pressure source may be required. If thelauncher is not equipped with valve 280 and venting is not desired(since it wastes pressurized gas), a vent valve located in free piston240 and a small pin device located inside pressure tube 110 can be used.During engagement of hold back mechanism 290, the pin could push thevent valve in free piston 240 allowing free piston 240 to unseal andfall to the pre-launch position. A small boost pressure charge from anexternal pressure source may be required to restore full launcherperformance.

FIG. 7 shows a larger scale view of free piston 240 forming a seal withend stop 250 as described above in reference to FIG. 4. An optional seal292 is shown between end stop 250 and pressure tube 110.

FIG. 8 shows the air vehicle 100 after being launched from tube 210.This embodiment is provided with two legs 270 positionable against tube210 in a stored position and deployable to the position shown in FIG. 8.Legs 270 are preferably adjustable to compensate for different terrainat the launch site.

FIG. 9 is a perspective view of an air vehicle 100′ in accordance withthe invention. In this figure, air vehicle 100′ is shown in the flying,unfolded state. Wings 130 pivot about shaft 138 from the closed (storageand launch) position to the open (flight) position under the force ofsprings or other urging devices. Tail 140 also moves from a folded(storage and launch) position to a open (flight) position after leavingtube 210 of launcher 200.

FIGS. 10 and 11 show an example of a mechanism that links the opening oftail 140 and wings 130. In this example, a linkage 136 connects a tailplug 148 to a slider 134 that is provided with a wing knife 132 thatengages wings 130 in the closed position. Upon tail 140 opening, tailplug 148 slides relative to fuselage 120 and, through linkage 136, movesslider 134 to fuselage 120. As a result, wing knife 132 moves relativeto wings 130 and disengages from wings 130 allowing wings 130 to openunder the force of, for example, springs.

FIG. 12 shows an example of a tail release mechanism. In FIG. 12, airvehicle 100 is being launched and pressure tube 110 is about to clearlaunch tube 230. Tail 140 (two tail fins are shown in this view) is heldin the closed position by at least one cam 144 that engage a lock recess146 in at least one of the fins of tail 140. A spring 142 attempts topush cam 144 into a cam recess 116 in the wall of pressure tube 110. Inthe position shown in FIG. 12, the progress of cam 144 through camrecess 116 is prevented by the presence of launch tube 230. As pressuretube 110 continues upward in FIG. 12 as the launch progresses, pressuretube 110 clears launch tube 230 and launch tube 230 no longer preventscams 144 from progressing through cam recesses 116 under the force ofsprings 142. As cams 144 progress through cam recesses 116, cams 144disengage from lock recesses 148 and allow the fins of tail 140 to moveto the open position under spring, or other, force.

It is to be understood that even though numerous characteristics andadvantages of the present invention have been set forth in the foregoingdescription, together with details of the structure and function of theinvention, the disclosure is illustrative only, and changes may be madein detail, especially in matters of shape, size and arrangement of partswithin the principles of the invention.

The embodiments illustrated and discussed in this specification areintended only to teach those skilled in the art the best way known tothe inventors to make and use the invention. Nothing in thisspecification should be considered as limiting the scope of theinvention. All examples presented are representative and non-limiting.The above-described embodiments of the invention may be modified orvaried, without departing from the invention, as appreciated by thoseskilled in the art in light of the above teachings. It is therefore tobe understood that the invention may be practiced otherwise than asspecifically described.

1. (canceled)
 2. (canceled)
 3. (canceled)
 4. (canceled)
 5. (canceled) 6.(canceled)
 7. (canceled)
 8. (canceled)
 9. (canceled)
 10. (canceled) 11.(canceled)
 12. (canceled)
 13. (canceled)
 14. (canceled)
 15. (canceled)16. (canceled)
 17. (canceled)
 18. (canceled)
 19. (canceled) 20.(canceled)
 21. (canceled)
 22. (canceled)
 23. A foldable unmanned airvehicle, comprising: a fuselage having a pressure tube portion forreceiving a launch tube of a pneumatic launcher; two wings, each wingbeing pivotably connected to the fuselage such that it pivots about apivot point; a wing retention mechanism that holds the wings in a foldedposition; a foldable tail connected to the fuselage; a tail retentionmechanism that holds the tail in a folded position; and a linkage thatlinks the wing retention mechanism to the tail retention mechanism suchthat release of one of the tail retention mechanism and the wingretention mechanism releases the other of the tail retention mechanismand the wing retention mechanism.
 24. The air vehicle of claim 23,wherein release of the tail retention mechanism releases the wingretention mechanism.
 25. The air vehicle of claim 23, wherein the airvehicle is configured for launching from a containment tube with thewings and the tail in their folded positions.
 26. The air vehicle ofclaim 25, further comprising a tail retention mechanism trigger fortriggering the release of the tail retention mechanism when the airvehicle exits the containment tube.
 27. The air vehicle of claim 26,wherein the tail retention mechanism trigger comprises spring loadedcams for pressing against the launch tube through holes in the pressuretube, wherein the spring loaded cams are released from engagement withthe tail when the launch tube is removed from the pressure tube.